Remove wildcard from scope_extensions, make a specialized entry

[dmurph]

The wildcard is a little weird for an origin, and it's not a parseable URL. We would have to specialize the parser for it.

  {
    "id": "/",
    "name": "Example",
    "display": "standalone",
    "start_url": "/index.html",
    "scope_extensions": [
      {"origin": "https://example.com", "treat_as_registrable_domain": true },
     // but this could also parse OK too:
      {"origin": "https://www.example.com", "treat_as_registrable_domain": true },
      {"origin": "https://www.example.co.uk"},
    ]
  }

This would allow only the www.example.co.uk part of example.co.uk, but allow ANY subdomain of example.com, as we treat the origin as a registrable domain.

Also, the spec already has a definition of registrable domain / eTLD+1, so we can parse that correctly. And we should likely require inclusion the https of the origin.

[dmurph]

@LuHuangMSFT

[alancutter]

I'm in favour of this change. We should stick with standard URL parsing if possible as there are likely edge cases this simplified form fails to handle.